Due to increased screenings with better screening tools breast cancer is detected earlier. This implies that higher resolution diagnostic tools are required for managing smaller sized tumors. Fluorodeoxyglucose positron emission tomography (PET) has been known to be an effective modality in staging primary tumors and monitoring chemotherapy. Research has shown that FDG-PET is capable of predicting pathological response of primary tumor to chemotherapy agents, but the spatial resolution of current systems limits them to tumors larger than 2 cm. The goal of this project is to prove that the spatial resolution of present dedicated breast PET/CT systems can be improved to sub millimeter spatial resolution using a high-resolution detector insert. In order to prove this principle this project aims specifically to construct and characterized a detector with tiny scintillating crystals made of lutetium oxyorthosilicate. This detector is then adapted to a dedicated PET system previously designed and fabricated in this lab. After this the combined performance of the high-resolution detector and the moderate resolution detector will be characterized. The spatial resolution after tomographic reconstruction and sensitivity will be measured. The proposed research plan is tailored to engage the applicant in the participation of translational cancer bioengineering research. The sponsor will provide the resources, space, and equipment for the applicant to carry out the necessary science and engineering tasks. A timeline of courses and field related seminars are included in the training plan to enhance the training experience. The accomplishments of the stated goals will better prepare the applicant in becoming a translational researcher and representative of Hispanic minorities in the field, hence promoting diversity.